Encrypted databases provide data protection (security) in cloud platforms and/or database-as-a-service (DaaS) settings. In encrypted databases, data (plaintext) can be encrypted at the client to provide encrypted data (ciphertext), which can be provided to the database for storage. In some examples, a third-party provides and maintains the database. That is, the database is outsourced to the third-party. For example, a client encrypts data using one or more encryption keys to provide encrypted data, which the client sends to the third-party for storage in the database.
Outsourcing a database offers efficient resource management and low maintenance costs for clients, but exposes outsourced data (client data) to a service provider (the third-party providing the database and its agents). For example, disparate query operations to be executed over encrypted data require varying levels of encryption, some less secure than other. Further, queries executed over the encrypted data can leak information to the third-party (e.g., access patterns) service provider, which can be used in cryptanalysis.